Dual cores

[cyberslag5k]

How exactly do dual cores impact performance? Is it essentially the same thing as having two processors within the same chip? And if so, is it such that the proc performs twice as "fast" as a single core unit operating at the same frequency (assuming all other things were the same)?

So let's say there are 5 instructions (a, b, c, d, and e) that need to be processed, each with an associated number of single-clock instructions:

a 10
b 20
c 1
d 10
e 5

So will core one process instruction a and core two process b? When one is done with a, will it move on to c, then d, and finally two will process e when it's done with b? Or will they split the work on each instruction? Or does it really only kick in for multi-threaded processes? How exactly does it work, and what are the implications performance-wise (roughly, anyway)?

 

[defakto]

In order to take advantage of multiple processors/cores a program needs to be a.) multi-threaded and be able to be parrellized and b.) your OS must support SMP.

It does not work like a single processor 2x as fast as a single processor. It works like 2 processors doing different jobs.

Think of it like two faucets in your house. You can use one or the other without problems to fill a single jug, but you can't use both without cheating(no cheating allowed for this scenario). BUT if you need to fill alot of jugs you can split the workload among faucets.

Depending on the application you can expect from 0 - ~90-95 percent increase in performance.